This invention relates to hydrophilic, lubricant coatings that make biomedical devices slippery when wet. The method and coating of the invention may be employed to reduce the coefficient of friction of catheters, condoms, contact lenses, peristaltic pump chambers, arteriovenous shunts, gastroenteric feed tubes and endotracheal tubes, or other implants of metal or polymer substrate.
Known lubricious coatings that may be applied to biomedical devices include coatings of polyvinylpyrrolidone (PVP), polyurethane, acrylic polyester, vinyl resin, fluorocarbons, silicone, rubber, or combinations of these substances. For example, Micklus et al., U.S. Pat. No. 4,100,309 and U.S. Pat. No. 4,119,094 relate to a hydrophilic coating of PVP-polyurethane interpolymer formed with polyisocyanate. Ratner et al., U.S. Pat. No. 3,939,049, relates to a method of grafting hydrogels to polymeric substrates using radiation Hudgin et al., U.S. Pat. No. 3,975,350, relates to hydrophilic polyurethane polymers. Stoy et al., U.S. Pat. No. 3,987,497, relates to a tendon prosthesis with hydrogel coating.
These known hydrogel coatings have disadvantages: They may have an insufficiently low coefficient of friction, they may lack permanence (such as silicone or fluorocarbons), they may be slippery when dry as well as wet, making handling difficult, or (such as the Micklus et al. coatings) they may require the use of hazardous solvents to prepare them and contain unstable, reactive materials, so that separate and new solutions must be prepared daily or more frequently.
Furthermore, in the PVP-polyurethane coatings, little control can be exerted over the degree of lubricity and resistance to wet abrasion of the coatings, and such coatings are often unstable.
In order to solve these problems a hydrophilic lubricant coating was needed which, when wetted, has sufficient lubricity to be useful for biomedical devices such as implants, which adheres to a wide variety of substrates and resists wet abrasion, and which can be prepared from chemically stable and biocompatible solvents.